Drawing instrument.



W. D. REES.

DRAWING INSTRUMENT.

APPLICATION FILED Nov.23. 1914.

1, 148, 1 22. Patented July 27, 1915.

COLUMBIA PLANOORAPN c0., WASHINGTON, D. C.

WILLiLaM a. miss, or coiiuiasus, onro.

DRAWING rns'rnuivrnnr.

Specification of Letters Patent.

- Patented Jul 27, 1915.

mama filed November 22, 1314. Serial no. 2,653.

TocZZZ whom it may concern: I

it known that I, WILLIAM D. Runs, a cit zen of the Umted States, residing at Columbus, in the county of Franklin and State of Ohio, have invented certain new and useful Improvements in Drawing Instruments, of which the following is a specification.

My invention relates to drawing instruments of the type known as ellipsographs.

Iy device is adapted for general use in drawing ellipses of the ordinary sizes used for all practical purposes in mechanical drawing and in the school room.

The main object of my invention resides in the provision of cooperating stock and slide members each carrying a focus arm in such relation that these arms be ,readil'y located in superposed relation with the foci of the ellipse tobe drawn. Each, of these arms carries a flexible tape member adjustable as to length whereby an ellipse may be readily drawn. 1

A further object of my invention resides in the provision of means whereby this flexible tape may be automatically shortened as to length, or, in other words, any undue slack not desired may be automatically taken up. Still a further object of my invention residesin locking this tape against extensible movement and also for locking the slide and stock members in any position of relative adjustment. o 7,

Further objects of my invention will appear from a detailed description of the aceo'i'npanying sheet of drawings, wherein similar characters of reference designate corresponding parts, and wherein: V

Figure 1 is a top plan view of my ellipsograph in its preferred embodiment and showing its manner of use, Fig. 2 is a similar view showing the slide and-stock members in their closed positions, Fig. '3 is an end "i'ew of the structureshown in Fig. 2, Fig. 1 is a side view of the structure shown in Fig. 2, Fig. 5 is a fragmentary section taken on line 55of Fig. 2, Fig. 6 is afragmentary section taken on line 6 6 .of Fig. 3, Fig. 7 is a section taken on 1i'ne7- 7 of Fig. 1, and, Fig. 8 is a section taken on line 88 of Fig. 2.

In the drawings, there is shown a stock member 1, this member being provided with a comparatively large fiat base and having its edges turned up and so formed to present slideways 2. Within these slideways, the slide member 3 is located, this slide member being so formed that a smooth upper surface ispresented level with" the uppermost portion of the stock member, while its slide projections I are arranged to 006perate with the slideways'2 to give the desired connection. Each of the stock and slide members carries an outwardly projecting focus arm 5 and 6-respectively, the ends of. these focus arms projecting to some considerable distance beyond the edge of the stock member and being each provided with a small aperture 7. A flexible tape member 8 is provided and so attached'that one of its ends is rigidly secured through the aperture 7 in the focus arm 6 and then passes through the aperture in the focus arm 5 to slidably engage the same. In the claims, I have claimed this feature by "stating that the tape is rigidlysecured at one end to one of said arms and 'slidably connected to the other. Inasmuch as the focus arm 6 is rigidly connected with the stock member, this stock nember and focus arm are in reality oneand, therefore, these claims do not riseessarily mean that the tape is se'cured to the focus arm as is shown in the drawings, but may be continued through the aperture 7 to be secured to the adjusting bolt 15 to be presently described, or to any other projection carried by eith'er the stock member or focus arm. The opposite end of the tape is attached to a'drum 9 rigidly mounted upon ashaft 10, the latter being suitably journaled in an upstanding bearing member 11 at one end and in a casing member 12 at its opposite end. In order that thetape 8 may be always maintained taut, Ihave provided spring means'in the form of the spiral spring 18 to edect the winding, one end of this spring being rigidly attached to the shaft 10, while its other end is rigidly attached to the casing 12. 1 I

The above structure is based upon the fact that the sum of the distance'sfrom any point on the curve of an ellipse to two fixed points called the foci is a constant and is also equal to the major axis. In all practical work, the maj or and minor axes are given and in using my instrument, these axes should be properly laid out. Then, by taking half the length of the major axis and describing an arefr'om one end of the minor axis, so that the major axis is intersected, one focus point may be determined. Similarly, the other focus point may also be readily located. lhen, so adjusting the slide and stock members that the apertures in the ends of the focus arms 5 and 6 are directly above these foci and by extending the tape, by the use of a pencil or similar instrument, to the end of the minor axis, as is shown in broken lines in Fig. 1, a true ellipse may be drawn by a movement of the pencil as is also indicated in Fig. 1, care being taken to always maintain the tape in a taut condition. In order to guard against a serious error in the outline of the ellipse, I have offset each of the arms 5 and 6 as indicated at 14 in Fig. 3, so that the under portion of the arms are slightly spaced from the plane of the underside of the stool: member, this space being only sulficient to permit a free movement of the tape as the ellipse is described. I have also provided a thumb screw 15 passing through the slide member and engaging the stock member, so that these two members may be rigidly locked in any adjusted position should this locking be desired. Further. I have also provided means for locking the tape 8 against any extensible movement. These means take the form of a leaf spring 16 bent to U-shape, one of the legs being rigidly attached to the stock member, while the other leg engages the underside of a thumb screw 17. This latter leg is also so disposed that it overlies a portion of the tape extending from the aperture in the end of the arm 5 to the drum 9. The end of the leg of this spring 16 bearing against the underside of the thumb screw 17 is also provided with a suitable rubber or similar cap 18 so that the tape itself will not be injured when the spring is forced into engagement therewith by turning of the screw 17.

From the above description taken in connection with the accompanying drawings, it will be apparent that I have provided a drawing instrument wherein ellipses. will be drawn with a great degree of accuracy. By the provision of the two locking means described, the instrument may be set for any desired size and permanently held in such position, if desired. Further, these adjustments render it unnecessary for the operator to manually hold the slide member and winding spool in any definite position when using the instrument.

What I claim, is:

1. An ellipsograph comprising a stock member, a slide member slidable in connection therewith, an outwardly projecting focus arm carried by each of said members, a flexible tape rigidly secured at one end to one of said arms and slidably connected to the other, a drum upon which said tape is arranged to be wound, and means including a positively held clamp adjustable to release or hold said tape locked with any given length between said focus arms.

2. An ellipsograph comprising a stock member, a slide member slidable in connection therewith, an outwardly projecting focus arm carried by each of said members, a flexible tape rigidly secured at one end to one of said arms and slidably connected to the other, and binding means including an adjusting screw adjustable to release or hold said tape to any position of adjustment.

3. An ellipsograph comprising a stock member, a slide member slidable in connection therewith, an outwardly projecting focus arm carried by each of said members, a flexible tape rigidly secured at one end to one of said arms and slidably connected to the other, and a drum to which the opposite end of said tape is attached, said drum being held in such position with respect to one of said focus arms that the length of tape between it and the end of the focus arm is the same for all sizes of ellipses.

l. An ellipsograph comprising astock member, a slide member slidable in connection therewith, a focus arm carried by each of said members and projecting outwardly in a direction substantially parallel withthe base of said stock member, a flexible tape rigidly secured at one end to one of said armsand slidably connected to the other, and a drum to which the opposite end of said tape is attached, said drum being carried by the top side of said stock member in a position in back of the end of the focus arm on the stock member.

5. An ellipsograph comprising a stock member, a slide member in connection with said stock member, a focus arm carried by each of said members, a flexible tape securely fastened at one end to one of said arms and slidably connected to the other, a drum upon which the opposite end of said tape is arranged to wind, said drum being carried by the top side of said stock member directly in the rear of its focus arm, and means adjustable to release or hold said tape locked with any given length between said focus arms.

6. An ellipsograph comprising a stock member, a slide member slidable in connection therewith, an outwardly projecting focus arm carried by each of said members, a flexible tape rigidly attached at one end to the end of one of said arms and slidably engaging the end of the other arm, a drum upon which said tape is arranged to be wound, and a locking device adjustable for positively holding said tape locked against winding movement on said drum.

7. An ellipsograph comprising a stock member, a slide member slidable in connection with said stock member. a focus arm carried by the upper side of each of said members, the portions of said arms projecting beyond said members being ofl'set to bring them closer to the plane of the base portion of said stock member, a flexible member, a slide member slidable in connec tion with said stock member, a focus arm carried by the upper side of each of said members, the portions of said arms projecting beyond said members being offset to bring them closer to the plane of the base portion of said stock member, a flexible tape rigidly secured at one end to one of said arms and slidably connected to the other, a drum to Which the opposite end of said tape is Wound, and means adjustable to release or hold said tape in any position of adjustment.

9. An ellipsograph comprising, a stock member formed of a fiat sheet Whose longitudinal edge portions are doubled back to form slideways, a slide member slidable in said slideways, a focus arm carried bythe upper side of each of said members, the portions of said arms projecting beyond said members being ofiiset to bring them closer to the plane of the base of said stock member, a flexible tape rigidly secured at one 7 end to one of said arms and slidably connected to the other, and a drum carried by said stock member to Which the opposite end of said tape is Wound.

In testimony whereof I alfix my signature inpresence of tWo Witnesses.

WILLIAM D. REES.

Witnesses:

WALTER E. L. BocK, A. L. PHELPS.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

